1. Field of the Invention
The present invention relates generally to improvements in hot exhaust gas pipes and mufflers and more particularly pertains to new and improved decorative exhaust gas pipes and mufflers used on motorcycles and customized automobiles.
2. Description of Related Art
One of the most critical problems confronting the developers of motorcycle exhaust pipes and mufflers or exhaust pipes and mufflers for automobiles which are exposed for appearance purposes has been the prevention of heat discolorization of the chromed exhaust pipes and muffler casings from the extreme heat generated by high engine performance.
Although the prior art has been concerned with preventing heat transfer to the outer housing of a motorcycle exhaust system, none have really accomplished that goal, none have prevented heat discoloration as the present invention. U.S. Pat. No. 4,356,885 for a Chambered-Core Motorcycle-Exhaust Apparatus was granted on Nov. 2, 1982 to Christy J. Dello. The exhaust system described in the Dello patent is concerned with a double wall exhaust system wherein the inner core is mounted within a tubular housing having a larger diameter than the inner core so as to establish an annular chamber between the outer housing and the inner exhaust core. Dello specifically requires the use of an inner exhaust core system that has a plurality of interconnected pipe segments.
U.S. Pat. No. 3,858,678 was granted Jan. 7, 1975 for a Muffler With Rotary Gas Flow to Ralph Haren. It is directed to a muffler construction that has an outer shell which is clamped to the ends of a flow tube which contains flow obstruction devices to prevent or restrict straight through gas flow.
U.S. Pat. No. 3,104,733 was granted Sep. 24, 1963 for a Sound Attenuating Gas Pipe to Edmund Ludlow. It is directed to an exhaust system which has an outer pipe with a plurality of sections or inserts mounted within the outer pipe that are coaxially aligned within the outer pipe to define a main gas flow passage therethrough. The combination is designed so that each adjacent pair of inserts act in combination with the adjacent wall of the outer pipe to define a xe2x80x9cresonating chamber of volumexe2x80x9d.
U.S. Pat. No. 5,799,395 was granted Sep. 1, 1998 and U.S. Pat. No. 5,907,134 was granted May 25, 1999 for Air Gap-Insulated Exhaust Pipe And Process For Manufacturing An Air Gap-Insulated Exhaust Pipe to Thomas Nording, et al. Both patents are directed to a double wall exhaust pipe wherein the inner pipe which is comprised of sections connected by a sliding fit which are prevented from contacting the walls of the outer pipe as the result of the thermal expansion of both pipes during operation. None of these prior art patents prevent the heat discoloration as does the present invention.
A decorative chromed exhaust pipe for internal combustion engines is provided which does not discolor from the heat generated by the exhaust gases flowing from the engine to the muffler. A double-walled muffler is completely encased by an interior pipe section which only allows gases to flow out the back end from the inlet end. The exhaust pipe, from the mounting flange to the muffler has a double wall construction with the exterior wall chromed. The exterior chromed pipe is cut-away on its back side, from the mounting flange to the muffler, allowing the interior one piece pipe to be inserted through the cut-away section. Mounting flanges are welded to the exterior and interior pipes at the back side for mounting the exhaust pipe to the vehicle and hold the interior pipe in a spaced apart relation to the exterior pipe. During operation, the cut-away back side of the exterior pipe provides cooling to the exterior pipe sufficient to prevent heat discoloration of the exterior pipe under the heaviest load conditions.